X c control apparatus



CONTROL APPARATUS Filed March 50, 1922 2 Sheets-Sheet 1 ,WMe/77W; WWW/77 Glop/reef 14 1927. l] (532 @74 June W. G. HOUSKEEPER 9 CONTROL APPARATUS Filed March 30. 1922 2 Sheets-Sheet 2 Patented dune lei, i927.

WILLIAM G. EOUSKEEEER, OF NEW YORK, N. Y., ASSGNOR TO WESTERN ELECTRIC COMFPANY, INCORPORATED, 0F NEVI 'YGBJIQ N. Y., A COREGRATION OF NEW YORK.

CGNTROL AEPARATUS.

Application filed March 30, 1922. Serial No. 548,076.

rlhis invention relates to electriccurrent control devices, and especially to a device for controlling the bombardment oi' the elec trodes of vacuum tubes during the evacuation thereof.

In the exhaustion ot vacuum tubes the gas occluded in the grid and anode electrodes isdriven out by heat developed in said electrodes through the bombardment thereoil by electrons emitted from the cathodeand driven against said electrode by the dil'erence ot potential between the cathodeand the other electrodes. The gas thus liberated is removed iii-om the tube by the exhaust equipment. lt is necessary to control the rate of bon'ibardment since itt gas is liberated from the electrodes faster than the exhaust equipment can remove it, the electrons will ionize the gas, thereby setting tree positive ions which will bombard the cathode and cause injury thereto. The control of the bombardment has heretofore been accomplished tl'irough a variation of the potential between the electrodes by the manipulation of rheo stats or switches by an operator.

An object of the invention is to automatically control the rate oit bombardment whereby the exhaustoperation will be carried on under the proper conditions without attention troni an operator.

Another object ont the 'invention is to utilize changes in pressure within the vessels of the electron discharge devices to vary the bonilnirdingcurrent.

Aanother object of the invention is a simple, economical and eliicient apparatus tor automatically controlling the evacuation ot the vessels ot electron discharge devices.

@ne type ont `device for accomplishing` these objects comprises an ionization ma.- noineter in communication with the vessel to be exhausted, the variations in current from ionization due to changes in pressure within the manometer tube being utilized to etiicet changes in the held between the cathode and other .electrodes of the tube being ei;- hausted. lnanot-her type of this device the grid and anode are mar-tainedk at ditlerent potontizfils and variations in the grid potential due to current from ionization are utilized to vary the lield between the cathode and anode.V y

Other objects and features et this invention will be apparent from the following specification and accompanying drawing wherein: Fig. l discloses one embodiment of the. invention; Figs. 2 to 6 disclose modified terms of the embodiment ot the invention shown in Fig. 1.

Tieterring now to Fig. 1, 10 is a header ot an emcuating apparatus in communication with which are vessels 11 to be evacuated. Also in communication with the header 10 is a bulb 12 of an ionization manometer, in'

which are contained a cathode 13, a grid la and a plate electrode 15. One terminal of the cathode 13 is connected tothe negative pole of a source ot direct current electrical energy 1G, preferably a generator, through a resistance 17. The other terminal is connected withthe positive pole of the source 1o through a resistance 18; The gridl: is connected to the positive pole of the source 1G through the winding of a relay 19, the movable contact 2O ot which is connected to the nega-tive lead of the cathode 13 and the stationary contact 21 of which is connected to the positive terminal of said cathode. in ammeter 22 is contained in the lead between the relay 19 and the source 16. The plate 15 is connected to the negative pole of the source 16 through a resistance 23 and an ammeter 24. Since the grid is maintained positive relative to the filament, a space current is caused to flow between these electrodes. The electrons ot the .space current ionize the gas in the vessel 12 and the positive ions flow to the plate 15 which is negative with respect to the other two electrodes. rl`his causes a flow of current in the plate circuit. rlhe space current flowing from the cathode 13 to the grid 14 is maintained substantially constant by virtue of the short"circuiting` ot the cathode through the closing of the contacts 2O and 21 whenever the current in the grid lead through the relay 19 tends to exceed a predetermined `value and the opening of said contacts when the current returns to said value. Any change in pressure within the vessel'causes a variation in the ionization currentthrough the plate lead which variation is indicated by the ammeter 2li. This arrangement of the ionization manometer is disclosed in my Patent 1,465,394 issued August 21, 1923.

The plate electrode l15 ot the ionization manometer is electrically connected with the grid 27 of an amplifier 28. The cathode 29 of the amplifier has one of its terminals connected to the negative side of the source 16 and has its other terminal connected to the positive side of said source through a resistance 3U. The anode 31 of the amplifier is connected with the positive pole of the source 16 through the Winding of a relay 32, the fixed contact 33 of said relay being connected to the lead from the relay to the source 16. The movable contact 34 of the relay 32 is connected. to a brush 35 of a l). C. motor 36 through the winding of a relay 37. A condoctor 38 leads from an intermediate point of a resist-ance 30 to the lead between the brush 35 and the relay 37. The other brush 39 of the motor 36 is connected to the movable contact 4() of the relay 37. 'Two stationery contacts 41 and 42 are provided, which are adapted to be engaged by the movable contact in its two positions respectively. The movable contact 40 engages the contact 42 when the relay 37 is dcenergized. The contact 42 is connected to the negative side of the source 16 through a switch 44 and a resistance 45. The contact 4l is connected with the positive side of said source through a switch 46 and a resistance 47. Each of the meistances and 47 is of a value several times that of resistance 30. The .field windin- 48 of the motor 36 is connected with the poes of the Source 16. This arrangement provides for the running of the motor 36 in either direction. The brush 35 is maintained at a, potential approximately midway between the otentials of the poles of its source 16 due to its connection to the resistance 30. The brush 39 is rendered either more negative or more `positive than brush 36 according to whether the contact 4() engages the contact 42 or the Contact 41. Current can `thus be made to flow through the armature of the motor in either direction by the proper arrangement of the contact 40.

The 't-Wo circuits for the motor are as follows: When the contact 40 engages the contact 42, asv shown in Fig. 1, beginning with the positive pole of the source 16, the circuit extends through the lower haltl of resistance 3f), conductor 38, brush armature of motor 36., brush 39, Contact 40, Contact 42, Switch 44, resistance 45, and to negative pole of source 16. When contact 40 engages contact 41, the circuit extends from, the positive poie of 16 through cathode 29, upper part of resistance 30, conductor 38, brush 35, armature of motor 36, brush 39, contact 40, contact 41, switch 46, resist-ance 49 and to the negative pole of 16. The motor current is so small in comparison to the heating current for cathode 29 that the flow thereof tl'lrough the cathode circuit does not a'ect the operation of the amplifier 28.

A screw threaded shaft 49 is driven by the motor 36, and on it is provided a rider 50 having threads to engage with the threads 0n the Shaft, whereby rotation of the sha-ft in opposite directions causes the rider to travel longitudinally in opposite directions along the shaft. Portions of the rider project beyond the `shaft and are adapted to engage with the movable part of the :switches 44 ,and 46 to. open them, springs being provided normally to hold said switches closed. These switches. 44 and 46 are provided to stop rotation of the motor armature 36 and thus prevent injury to shaft 49 and rider 50, when the rider 50 is in either of its extreme end positions. The rider 50 carries 4a contractor 51, one portion of which is in contact With and slides along a bar 52, :md another portion of which wipes along a resistance 53. The bnr 52 isy `connected to fthe positive pole of a source of D. C. electrical energy 54, preferably a generator, `the negative po e of which is connected to the negative terminale of the cathodes 55 of the devices to be exhausted. The resistance 53 is connected with the grids and anodes 56 and 57 of said devices through the resistances 58. Heating current is suppiied to the cathodes 55 from a source of alternating current 59.

The resistances 58 essere simultaneous bombardment in all of the devices 11 as they compensate for any dence in `the internal resistance of the devices and thereby prevent such a dierence in resistance between the various devices as would allow substantialiy all the current to ofw through the device having lthe iowest internal resistance. Thus, the starting of the discharge in one of the devices does not materially affect the potential drop across the devices and thedischarge will start in all the devices at approximately the same time.

The operation of this device is as fdifrws: After a comparatively high vacuum has been obtained within the vessels 11 by the exhaust apparatus, heating currentV is supplied to the cathodes 55 from the source 59 and a difference of potentiel is established between the cathodes and 56 and :modes 57 from the source 54; the rider 50 is p}aced at approximately its extreme light-hand position, the contact 40 being in engagement with the contact 42 and the contacts 34 and 33 being ont of engagement. At the sume time, heat-ing current is supplied to the cathodes` 13 and 29 from the source i6, the plate 15 is rendered negative, and the grid 14 positive with respect to cathode 13. The plate 31 is positive, and the grid M siightly positive, with respect to cathodes 29 because of the resistance 23.

'The direction of current How tlmmgh the motor 36 is such that the screw 49 rotates in a direction to move the rider 50 to the left thereby decreasing the resistance 53 md increasing the fiod between the electrodes 55 and 56 and 57. The bombardment of the grids and anodes 56 and 57 by the electrons heats them and liberates therefrom the occiuded gases. The liberation of these gases causes an increase in pressure in these vessels and also in the bulb 12 ot the ionization .nianonieteiz As a result oi the increase oi pressure in the bulb l2. there will be an increase in the ionization current tlowing through the plate lead. This will cause an increase in the potentialdrop across the resistance 23 and will therefore make the grid 27 more positive. The space current of the amplil'icr 28 is thereby increased to a sutilcient value to energize the relay 32, thereby closing the circuit through the relay 37, thus disengaging the contact 40 from the contact 42 and bringing it into engagement with the contact 4l. rlhe direction ot flow of current through the motor 36 is thereupon reversed and the motor is caused to rotate the sha'lt 49m such a direction as to move the rider 50 to the right, thereby increasing the resistance in the plate circuits ot' the devices ll. rlhe intensity of the lield between the cathodes and the grids and anodes 56 and 57 is thereby decreased and the heating effect diminished. The rate of liberation of occluded gases from the electrodes is thereby reduced. rihis action continues until the pressure is reduced within the devices ll :nid the bulb l2 to a point where the ionization current in the plate lead 15 drops below a ,predetermined value. The potential of the grid 27 thereupon is diminished suiiiciently so that the space current in the amplifier 28 is no longer strong enough to energize the relay 32, whereupon the contacts 33 and 34 are separated. rlhe relay 37 is then deenergized, allowing` the contact'40 to be separated Jfrom contact 4l and brought into its normal engagement with contact 42. The direction of current flow through the motor 36 is now the same as at the start oit the operation. The above cycle is repeated as the vpressure changes due to the rate of liberation of the occluded gases until the gases have been suiliciently removed. The degree of pressure is determined by reading the ammeter 24. lThe rate of liberation of the occluded gas is thus controlled, and the pressure within the vessels main tained at a value at which there is no danger oit destructive bombardment ot the cathodes 55 by the positive ions.

Although the relay 32 is shown as being included in the output circuit of amplifier 28, it is apparent that the amplilier might be dispensed with and the relay 32 be included in the output circuit ot the manometer l2.

Referring new to Fig. 2, 60 is the device to be exhausted and 12 is the bulb of an ionization manometer. The arrangement of the ionization manometer is the same as that in Fig. l, except that the plate lead of the ionization manometer is connected to the negative terminal of the cathode 29 of an electric discharge device 28. The cathode 29 is supplied with heating current -from a battery 6l. The. grid 27 is connected to the lead between the resistance 23 and the negative pole of the source 16. The anode 3l is connected with the negative terminal of the cathode 55, said cathode being supplied with heating current from battery 62. rl`he grid 56 and anode 57 are connected with the positiiepole of the direct current source 54 through the resistance 53, and the negative pole of said source is connected to the negative terminal of the cathode 29. Thus the bombardment current of the device 60 is the space current of the device 28. During the operation, an increase in pressure in the bulb l2 causes an increase in the ionization current, thereby increasing the potential drop across the resistance 28. This causes the grid 27 to become more negative with respect to the cathode 29, thereby decreasing the space current in the device 28, which is the current flowing troni the cathode 55 to the other electrodes of the device 60. The rate of liberation of occluded gases is thereupon decreased until the ionization current is reduced and thc grid 27 becomes less negative with respect to the cathode 29 thereby allowing an increase of space current in the device 28.

ln Fig. 3 the device 1l to be exhausted is in communication with the header lO of the evacuating device. The cathode 55 is supplied with heating current by a battery 63, and its negative terminal is connected to the negative pole of the source 54. The grid and plate electrodes 56 and 57 are connected to the positive pole of the source 54 through the winding of a relay 64 and resistances 65 and 66. The movable contact 67 of the relay 64 is in series with the winding of the relay 68, battery 69 and stationary contact 70 of the relay 64. The movable contact 7]. of the relay 68 is connected to the lead from the relay 64 to the resistance 65, and the stationary contact 72 of the relay 68 is connected to the lead between the resistances and 66. Under normal conditions, the contact 67 is out of engagement with the contact 70, and the contact 7l is in engagement with the contact 72. As the pressure within the vessel ll increases due to the liberation of occluded gases, the resistance within the tube decreases and the space current increases. T he relay 64 is thereupon energized and brings the contact 67 vinto engagement with the contact 70, thereby closing` the circuit through the relay 68. The relay 68, being energized, separates the Contact 7l from the contact 72 and introduces the resistance 65 into the plate circuit.` rl`he space current is thereupon decreased, and the rate of libera- "lll tion of oocludedgases is diminished until the current in the plate circuit is no longer strong' enough to energize the relay 64, whereupon the contacts 67 and 7() separate. The relay 68 is deenergized and contacts 7l and 79. move into engagement, thereby short,- circniting the resistance 65.

Although, in each of the nioditications above described, the grid and anode are electrical'lv connected and siniultziiicouf-ily boinbarded. itl is apparent that either of them may he separately bombarded.

In Fig. 4:, 11 is the device to be exhausted and in communication with the exhaust header 10. In communication with the header 10 is the bulb 12 of the ionization manometer, .the arrangement of which is the same as that described in connection with Fig 1, except that one terminal of the cathode 55 of .the device 11 is electrically connected with the lead between thc plate l5 of the ionization mauometer und theresistance 23. The remaining termin-.il ot the cathode 55 `is connected to the negative pole of the source 54, the positive pole ot which is connected to the plate 5T through the rcsistance 58. Heating current is supplie! to the cathode 55 from the generator 73. The grid 56 is connected to the lead between the resistance E23 and thesource ot energy 16. The operation of this arrangement is as follows: An increase in pressure in the manometer bulb 12 causes an increase ot ionization current in the plate circuit, thereby increasing the potential drop across the resistance 23. The grid 56 of the device to be exhausted is therefore rendered more negative with respect to the cathode and reduces the space current flowing` troni the cathode 55 to the anode 57. The heating of the anode is thus diminished. and the rate of liberation of gas decreased. Vhen the pressure within the bulb 12 has been reduced by the evacuation apparatus, the ionization current in the plate circuit ot the manmneter 12. becomes smaller and the potential drop across the resistance 23 is reduced. The grid 56 thereupon assumes a potential negative with respect to the cathode 55 and the space current increases.

Referring to Fig. 5, l1 is the device to be exhausted. The cathode is supplied with heating current from thesource 73. The anode 57 is connected with one terminal of the cathode through a resistance 58 and a source of D. @ocurre-nt 54. The grid 56 is connected to the plate circuit between the source 54 and the cathode 55 through the winding of the relay 76. the battery 77, resistance 78 and battery 79. Shuutcd around the battery 77 and the resistance 78 are the movable and stationary contacts 8O and 8l, respectively, for the relay 76. The batteries 77 and 79 are so poled as to make the grid 56 negative with respect to the cathode 55.

.therefore becomes smaller' and the relay The cont-acts 80 and 81 are normally in en gagenient, thereby shunting out the battery 77. .als the pressure increases Within the bulb .12, the current flowing in the grid circuit due to ionization energines t e relay T6, thereby separating the Contact members 8() and 8l. This action introduces into the plate circuit. the additional voltage drop through the battery 77 and renders the grid more negative, thereby increneing the resistance to the space current. in the device 11. As the space current decreases, the temperature olf the plate 57 drops and the rate ot' liberation of occluded gas diminishes. The ionization current in the grid circuit is deencrgized, thus allowing 8O and 8l to come into contact, thereby shunting out the battery 77.

.ln Fig. 6. the cathode 55 of the device to be exhausted is Supplied With beating current troni the battery 82. The negative terminal ot' the cathode is connected to the positive brush ot a series dynamo 83, the negative brush ot' which is connected t0 the grid 56 through the iield Winding 84 of the dynamo. The anode 57 is Connected with the positive pole ot a source off electrical energy 54 through the resistance 5S, and the negative pole of the source 54 is connected to the positive pole ot' the dynamo 83. When no current passing through the grid circuit, the residual magnetism of the field polesl ot' dynamo 83 produces a slight negative potential on the grid. As the pressn within the device 11 increases, a positive ionization current is caused to flow in the grid circuit, thus increasing the field strength and causing an increase in the potential drop across the terminals of the armature of the dynamo, thus rendering the grid more negative with respect to the cathode. The incre-ase of the negative potential on the grid with respect to the cathode increases the resistance of the tube and cuts down the space current flow. The rate of bombardment ot' the anode 517 is thereby decreased and the rate of liberation of occluded gases diminished. This action continues until the ionization current in the grid circuit has diminished sufficiently to render the grid less negative With respect to the cathode. The space. current then increases and the cycle of operations is repeated.

In each of the modifications disclosed in Figs. 4, 5 and 6. the grid electrode may be freed of its occluded gases by interchanging the connection ot the grid and anode so as to make the grid act as the collector ot positive ions or, ii the anode surrounds the grid, heat radiated against the grid from the anode may bring the grid up to the proper temperature to drive oil' the ocoluded gases.

It is to be understood that various modi- `matically varying iications maybe made in this device without in anyway departing from the spirit ot the invention set forth in the appended claims.

1What is claimed is:

l. ln a devicefoli the character described, an electric discharge device to be evacuated, said device comprising avessel containing a plurality oiLl electrodes, i-ieans to cause one of said electrodesto emit electrons, a source oil potential connected between said electron emitting electrode and' another ot said ele:- trodes i'or establishing a space current therebetween, and means controlled by the pressure of the gas within the device tor autothe potential oiE said source.

2. in a device ot the character describeI1 an electric discharge device to be evacuated,

said device comprising a vessel containingk i a plurality or electrodes, means to cause one of electrodes to eiiiit electrons, means to establish a space current between said electroireinitting,electrode and ano er olf scid electrodes, an ionization inanoiiieter in coinmunication with said vesseli and means controlled by variations in the intensity of the positive ionization current et said manometer for varying the intensityoil the space current in said electric'discharge devire.`

3. in a device ci the character described, an electric discharge device to be evacuatr said device comprising a vessel conta'r g aplurality et electrodes, ineens to canse one of said electrodes to emit electrons, means 'to establish a space current between said electron emitting electrodeand another of said electrodes, an ionization niaiioineter in communication with said vessel, and means controlled by'variations in the intensity ot the positive ionization current of said manometer for varying the intensity of the space current in said electric discharge device, said controlling means including means for amplifying said positive ionization current.

4l. In a device oi' the character described an electric discharge device to be evacuated, said device comprising a vessel containing` a plurality ot electrodes, means to cause one of said electrodes to emit electrons, means to establish a space current between said electron emitting electrode and another or' said ypressure of the gas within said vessel.

5. In a device oi" the character described, an electric discharge device to be evacuated, said device comprisingl a vessel containing a plurality of electrodes, means to cause one of said electrodes to emit electrons, means to establish a space current between said elec- Y tron emitting electrode and another or' said electrodes, an ionization inanometer in coiniiuiiication with said electric discharge device, means for varying tlie'intensity or the space current in said electric discharge device, andmeans iorv operating said current varying means, said means comprising current responsive meansvin the output circuit ot said amplifier, an amplifier, and means l'or varying the space current or said ampliher, said means being controlled by the ionization current of said maiiometer,

G. In a device or the character described, an electric discharge device to be evacuated, said device comprising a vessel containing a plurality of electrodes, means to cause one oit said electrodes to emitelectrons. means to establish a space current between said electron emitting electrode and another of said electrodes, motor driven means for varying the space current 0f said electric discharge device and means for operating the motor, said means being controlled by the pressure of the gas within the vessel.

'i'. ln a device of the character described, an electric discharge device to be evacuated, said device comprising a vessel containing a plurality of electrodes, means to cause one of said electrodes to emit electrons, means to establish a space current between said electron emitting` electrode and another of said electrodes, means for varying the space current of said electric discharge device comprising a variable resistance, motor driven means for eiieeting a change in said resistance and means for operating said motor in opposite directions, said means being controlled by the pressure of the gas within the vessel.

8. In a device of the character described, an electric discharge device comprising a vessel containing a plurality of electrodes, means to cause one of said electrodes to emit electrons, means to establish space current between said electron emitting electrode and another of said electrodes, an ionization manometer in communication with said electric discharge device, means for varying the space current Within said electric discharge device comprising a variable resistance, motor driven means for eiecting a change in said resistance, an amplifier, means in the output circuit of said ampliiier responsive to current variations for controlling the direction of rotation of said motor, and means for varying the space current of said amplifier in response to variations in the positive ionization current of said manometer.

9. In a device of the character described, an electric discharge device to be evacuated, said device comprising a vessel containing a plurality of electrodes, means to cause one :a space current between said electron emitting electrode and another of .said electrodes, an ionization manometer in communication with said device and means responsive to changes in the positive ionization currentin said manometer for verving the space current insaid electric discharge device, said means comprising; an maplier, means for rendering the potential ot' thc grid of said amplifier responsive to variations in the posit-ive ionization current of said umnonieter, means in the outputwircuit of said :impliier responsive to changes in the space current of said amplifier and means controlled by said current responsive means i'or varying the space current of" said device to be evacuated.

"11. In a device of the character described, an electric dischurgedevice to be evacuated, said device eon'il'irieing a vessel containingr a plurality of electrodes. means to cause one of said electrodes to emit electrons, means for establishing a space current in said device, said means comprising a source of energy and a variable resistance, motor driven means for operating said variable resistance, means for determining the 'i tion of operation of said motor, an ioninafy tion manometer in communication*with'saidI device, an amplifier, connections between said manometer andv said `amplifier whereby change in the positive ionization current of' said manometer produces change of pettine" tialof the grid ofv said amplifier and means in the output circuit of saidfamplierfr sponsive to changes in the space current tor mi controlling the operation of said means lfor determining the direction of rotation'ofseid motor. i

12. In a device of the character describedi,

a plurality oi electric dischargedevices {S0-lili' be evacuated, each of said devices compris-1 ing a vessel containing zu plurality of electrodes, means for causing one electrode off each device to emit electrons amd means fm* establishing a space current between each of 00 said electron emitting electrodes andanother vof the electrodes in the same Wel said means comprising a source of electritimlii energy, parallel connections from one ter minal` thereof connected to slid' electron 65` emitting electrodes and parallel'conneetinns lrm'n the other terminal therellf` w the other" electrodes, said last` named comiee'tion'comprising resistance units.

13. In a device of the character described, T0

a plurality of electric discharge devcesito" he evacuated, each of saidl devices comprising a vessel containing electrodes, means tor establish a space current between each* set ot' electrodes, and means controlled by the 75 

